基于可靠度理论考虑验证荷载的既有桥梁评估分项系数研究  

Study on partial safety factors for assessment of existing bridges based on reliability theory considering verification loads

作　　者：徐望喜 钱永久[1] 张方[1] 金聪鹤 黄俊豪 Xu Wangxi;Qian Yongjiu;Zhang Fang;Jin Conghe;Huang Junhao(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,成都610031

出　　处：《东南大学学报（自然科学版）》2022年第2期222-228,共7页Journal of Southeast University：Natural Science Edition

基　　金：国家自然科学基金资助项目(51778532)。

摘　　要：为准确评定既有桥梁的运营安全性能,基于可靠度与贝叶斯更新理论提出了综合考虑评估基准期与历史服役荷载的评估分项系数取值方法.根据5种不同风险准则确定相应基准期下目标可靠度,利用抗力优化法对构件进行评估分项系数取值分析,引入贝叶斯更新理论分析考虑历史服役荷载的评估分项系数取值,并与规范法、设计值法计算的评估系数在某一简支T型梁桥安全性评估上进行对比分析.结果表明:验活比(验证荷载效应标准值与活载效应标准值之比)为0.8、1.0时,考虑验证荷载后与考虑验证荷载前评估分项系数比为1.0.对于二级结构安全等级构件,抗力评估分项系数比取值为1.0;验证期为10、20、30、40 a时,荷载评估分项系数比在验活比为1.5时分别取0.94、0.81、0.69、0.69,在验活比为2.0时分别取0.88、0.75、0.63、0.50.采用建议的评估分项系数进行桥梁结构安全评估能充分挖掘结构潜在承载能力,更好控制桥梁结构的运维成本.In order to accurately assess the operational safety performance of existing bridges, an evaluation partial safety factors method based on reliability and Bayesian update theory is proposed, which considers the assessment base period and historical service loads. The target reliability indicators under different base periods are determined according to five different risk criteria, and the assessment partial safety factors are calculated using the resistance optimization method, which is further modified by introducing Bayesian update theory to consider the proof loads. It is compared with the assessment coefficients calculated by the code method and the design value method on the safety assessment of a simply supported T-beam bridge. The results show that the assessment partial safety factor ratio(after/before consideration of the verification load) is 1.0 when the verification live load ratio(the ratio of the standard value of verifying load effect to live load effect) is 0.8 and 1.0. For secondary structural safety rated members, the value of the resistance assessment partial safety factor ratio is 1.0. For the validation periods of 10, 20, 30 and 40 a, the load assessment partial safety factor ratios are taken as 0.94, 0.81, 0.69 and 0.69 at the verification live load ratio of 1.5;and 0.88, 0.75, 0.63 and 0.50 are taken at the verification live load ratio of 2.0, respectively. Compared with the code method and the design value method, the use of the proposed assessment factors for structural safety assessment can fully explore the potential load carrying capacity of the structure and better control the operation and maintenance costs of the bridge structure.

关 键 词：桥梁工程 分项系数 极限概率状态评估 在役桥梁 验证荷载 

分 类 号：U441.2[建筑科学—桥梁与隧道工程]